[unreadable] Gene repair by oligonucleotides produces targeted alterations in the genome of mammalian cells. We have made significant progress toward understanding the mechanism of oligonucleotide-based gene repair and applying the strategy to gene repair of skin. Our recent findings include; (1) in vivo gene correction of keratinocytes in murine skin may occur at a higher level than that in tissue culture and (2) various forms of oligonucleotides, RNA-DNA oligonucleotide (RDO) and single-stranded oligodeoxynucleotides (ODN), are both capable of gene alteration. Several characteristics of these oligonucleotides make them attractive for in vivo application in epidermis. Accessibility of the tissue makes it possible to administer therapeutics locally and to monitor both the treated and control sites. During our in vivo study, we observed a surprisingly high level and long-lasting gene alteration in murine skin. These findings suggest that oligonucleotide-based gene repair may be capable of epidermal stem cell gene correction and expansion of such cells may result in an apparently high level of gene correction in epidermis. Based on these results, we propose to correct the dominant mutation in murine keratin 14 gene found in Dowling-Meara Epidermolysis Bullosa Simplex (EBS) patients. Recently, Dr. Roop's laboratory generated an elegant transgenic EBS model where a dominant negative mutation was induced only in a focal area of skin. Here, we will test whether ODN can correct a dominant mutation in these neonatal transgenic mice and whether induction of blistering can be either prevented or diminished by in situ application of ODN to skin. Once basal keratinocytes are corrected, such cells will have proliferative advantage over mutated cells. If successful, this proof-of-principle experiment will lead to a potential clinical application of oligonucleotides to severely affected areas of EB patients for treatment. [unreadable] [unreadable]